This invention relates to an adaptation system for adapting a deformable model comprising a plurality of model elements to an object of interest in an image data set.
The invention further relates to an acquisition system for acquiring an image data set comprising said adaptation system.
The invention further relates to a workstation comprising said adaptation system.
The invention further relates to a method of adapting a deformable model comprising a plurality of model elements to an object of interest in an image data set.
The invention further relates to a computer program product to be loaded by a computer arrangement, comprising instructions for adapting a deformable model comprising a plurality of model elements to an object of interest in an image data set.
An embodiment of the adaptation method of the kind described in the opening paragraph is known from an article “Shape constrained deformable models for 3D medical image segmentation” by J. Weese, V. Pekar, M. Kaus, C. Lorenz, S. Lobregt, and R. Truyen, hereinafter referred to as ref. 1, published in 17th International Conference on Information Processing in Medical Imaging (IPMI), pages 380-387, Davis, Calif., USA, 2001, Springer Verlag. This article describes a method employing a deformable model represented by the triangular mesh. The triangles of the mesh interact with each other via internal forces. The internal forces oppose model deformations. In addition, each triangle is attracted via an external force to its detected corresponding target location in the image. In that sense, the location of each triangle is image-driven. The model energy is defined as a sum of an internal energy term, which depends on the locations of the triangles relative to each other, and on an external energy term, which depends on the locations of the triangles relative to their corresponding detected locations in the image. The two terms correspond to the aforementioned internal and external forces, respectively. At the minimum of the model energy all forces acting on the model are balanced and the model is at equilibrium. Finding the equilibrium locations of the triangles of the triangular mesh representing the deformable model, said locations corresponding to the minimum of the model energy, yields the adapted deformable model. The adapted deformable model is used to describe the shape and structures of the object of interest. The results of a study of CT images published in ref. 1 show a good overall adaptation of the employed deformable model as reflected by the mean distance between the surfaces of the deformable model and of accurate reference segmentation. There are, however, a few problematic areas in the deformable model, where distances between the surfaces of the adapted deformable model and of the accurate reference segmentation of the object of interest may exceed a few times the mean distance.